This invention relates to a suspension, guidance, propulsion and directional switching system for a high-speed electrodynamic suspension (EDS) magnetically levitated (maglev) vehicle and more particularly, to a maglev system in which a series of interlinked coils or loops are mounted on a flat or multi-slitted surface or guideway. This system provides suspension, lateral guidance and propulsion for the vehicle. The invention further includes changes in the active coil patterns to provide guideway directional switching.
The EDS maglev suspension and guidance system uses the repulsive magnetic forces generated by the interaction between the magnetic field produced by the eddy currents induced in the guideway mounted conductors and the magnetic field of the superconducting magnets (SCMs) aboard the vehicle to provide the required suspension and guidance for the system. Historically, several EDS suspension systems have been employed: continuous sheet suspension, loop-shaped coil suspension, and null-flux coil suspension.
The continuous sheet suspension system uses continuous conducting sheets oriented beneath the moving SCMs to provide suspension for the maglev. In this case, the repulsive suspension force is generated from the interaction between the magnetic field produced by the SCMs and the magnetic field generated by the eddy currents induced in the conductive sheet by the moving SCM field. This interaction provides a force normal to the plane of the sheet and, thus, levitation for the vehicle. The sheet, however, does not provide a stable guidance force for the vehicle. The guidance force is a force which is oriented in a direction perpendicular to the direction of motion of the vehicle and the suspension force. To obtain a stable guidance force, for this system, other conductor arrangements are required.
The single row loop-shaped coil suspension operates along a similar principle similar to that of the continuous sheet. With this system, the repulsive suspension force is generated as a result of the interaction between the magnetic force of the SCMs and the magnetic field produced by the induced eddy currents in the loop-shaped coils. This technique provides a large lift-to-drag ratio relative to the continuous sheet system. However, like the continuous sheet system, the loop-shaped coil suspension system cannot provide a stable lateral guidance force.
The combined null-flux coil suspension system consists of two vertically-oriented arrays of figure-eight-shaped loop-shaped coils arranged so that each single upper and lower loop coil is cross-connected to form a figure-eight-shaped null-flux coil and each array of figure-eight-shaped null-flux coils on the left-hand side of the guideway are connected with those on the fight-hand side to form a combined system. As a result of the cross-connections, a current flowing clockwise in the upper coil would flow counterclockwise in the lower coil, or reciprocally a counterclockwise current in the upper coil would result in a clockwise current in the lower coil. The combined null-flux coil arrangement is superior to either the continuous sheet suspension or the loop-coil suspension because it can function both as a means of supplying stable levitation forces and guidance forces. The combined null-flux system, also, has a high lift-to-drag ratio and a high guidance-to-drag ratio. This system is currently employed in the Japanese EDS maglev system. One of the main disadvantages of this system is that it requires side walls to support the null-flux coils and it needs to have cables crossing back and forth across the guideway to provide cross-connections to produce both suspension and guidance forces. When an energized coil, for example an SCM, passes midway between the null-flux coils, no net current is induced in the null-flux coils because they are cross connected or counter wound hence the term "null-flux". When the SCM is displaced from the midplane or neutral position relative to the upper and lower null-flux coils, a large net current is induced in the coils with the result that a strong repulsive force acts to restore the SCM to the neutral or "null-flux" position. A disadvantage of the current null-flux system designs is that it tends to couple lateral displacements with rolling and yawing motions. Some maglev design concepts utilize the same vehicle magnets to perform more than one of the basic functions, suspension, guidance, or propulsion. This multiple tasking occurs when the vehicle magnets interact with suitable guideway mounted devices.
The guideway directional switches currently employed by Germany and Japan in their maglev system designs require either physically bending or moving a section of concrete guideway to change the direction of motion of the maglev vehicle. Applicants' double row loop coil EDS suspension and guidance system can overcome the limitations in suspension, guidance, and directional switching systems referenced above.
Thus, it is an objective of this invention to provide a suspension, guidance and propulsion system which can be mounted on an unbounded platform or guideway, therefore, eliminating the need for sidewalls. In the alternative, the outer edge of the coils for each row can be bent to form a multi-slotted system which also eliminates the need for sidewall mounted coils.
A further objective of this invention is to provide for an electromagnetic guideway directional switching system to control the direction of travel of the maglev vehicle.
An additional objective of this invention is to configure the loop-coils on one side of the switching mechanism different from the coils on the other side of the mechanism to control the tilt angle of the maglev vehicle during directional switching.
Additional advantages, objects and novel features of the invention will become apparent to those skilled in the art upon examination of the following and by practice of the invention.